Production requirements for gasoline fuels have limited the amount of benzene permitted, creating a strong incentive for removing benzene from high octane fuel mixtures. Conventional catalytic reforming has been employed in production of gasoline by converting low octane paraffinic naphtha to high octane blending mixtures rich in benzene, toluene and xylenes (BTX). U.S. Pat. No. 3,729,409 (Chen) discloses a catalytic method for improving the yield-octane number of a reformate by contacting the reformate in the presence of hydrogen over a zeolite catalyst, such as medium pore ZSM-5. "Shape Selective Catalysis in Industrial Applications" by Chen et al (Marcel Dekker, 1989) describes a post-reforming process, "M-Forming", wherein ZSM-5 functions to crack paraffins and alkylate benzene present in the reformate. Conversion of alkenes and alkanes to produce aromatics-rich liquid hydrocarbon products was found by Yan et al. U.S. Pat. No. 3,845,150 to be effective using the ZSM-5 type zeolite catalysts in a fluid bed process. In U.S. Pat. No. 4,827,069, Kushnerick et al. describe fluid bed alkylation of benzene with lower olefins for upgrading reformate.
Prior art catalytic processes for benzene reduction in reformate typically do not provide a large benzene conversion in a single pass unit operation. This deficiency limits the amount of benzene that can be effected in continuous catalytic operations.
It has been discovered that hydrocarbon mixtures of benzene and paraffins, such as C.sub.6 -C.sub.8 n-alkanes and isoalkanes, can be upgraded efficiently in a continuous fluidized catalyst process to achieve at least 45% benzene conversion in a single pass operation. It has now been found that contacting a catalytic reformate feed comprising benzene and C.sub.6 to C.sub.8 alkanes and other hydrocarbons with a zeolite catalyst that the benzene can be converted effectively to lower alkyl aromatic hydrocarbons while at the same time converting lower value alkanes to higher value C.sub.5.sup.+ hydrocarbons, both of which products are suitable for use as gasoline blending stocks.